Now that the Obama administration has decided to go forward with both military trials and indefinite detention at Guantánamo, it has yet to resolve a key element: How does the Pentagon plan to execute war criminals condemned to death?

The question is particularly ripe as the Pentagon prepares its case against a Saudi-born captive blamed for the al Qaeda bombing of the USS Cole, Abd al Rahim al Nashiri, 46.

Suicide bombers killed 17 American sailors aboard the $1 billion destroyer off the coast of Yemen in October 2000. Pentagon lawyers during the Bush administration prepared a death penalty prosecution of Nashiri that alleged he was a co-conspirator.

His case is sure to stir controversy. The CIA acknowledges it waterboarded Nashiri, a self-described one-time millionaire from Mecca, before his September 2006 transfer to Guantánamo. The Associated Press also reported that a CIA agent revved an electric drill near Nashiri’s head and wielded a handgun during interrogation in a secret “black site” in Poland in 2002-2003.

Secretary of Defense Robert Gates or his successor gets to decide how to carry out a military commissions execution under the latest Manual for Military Commissions, said Army Lt. Col. Tanya Bradsher, a Pentagon’s spokeswoman. But the manual does not spell out a method or venue.

Pentagon lawyers refused this week to say whether Gates had begun the process of soliciting suggested methods -- lethal injection vs. firing squad, for example. Nor would Defense officials say whether the military bureaucracy that prides itself on constant planning and readiness had already selected an execution site on the remote 45-square-mile U.S. Navy base that has an elementary school for sailors’ kids, golf course for off-duty troopers and church services for a variety of faiths.

One issue, they said, was whether the war court that Obama disparaged as a senator then reformed as president would follow the federal model of lethal injection. The last time the U.S. military carried out an execution it hanged an Army private at Fort Leavenworth on April 13, 1961, for the rape and attempted murder of an 11-year-old girl in occupied Austria.

Where to hold an execution could also present a problem. Bush administration era consideration of using the federal facility at Terra Haute, Ind., may be mooted by Congress’ ban on the Defense Department’s use of federal funds to move any war on terror captive from the base to U.S. soil. For any purpose.

"Why would we answer this question now?," said one senior Defense Department lawyer. "There are no cases with charges pending, let alone capital charges, and even if there were, this question is seriously premature."

Only six Guantánamo captives have been tried at the various versions of military commissions that George W. Bush created in response to the 9/11 attacks, and none faced the possibility of a death penalty.

But Obama era lawyers withdrew those charges and suspended any new trials until this week. Now Gates has lifted the ban and authorized prosecutors to file changes against Nashiri but not any of the 9/11 accused.

Attorney General Eric Holder wants that case tried before a civilian jury near the spot where the World Trade Center once stood, as terrorism not a war crime. Prominent New Yorkers and members of Congress oppose that strategy as risky, fearing that federal judges may toss out evidence as tainted by the captives’ years of CIA captivity and that al Qaeda would seek to disrupt a Manhattan trial.

Thursday, nine Republican Senators led by former Vietnam war POW John McCain introduced legislation to reinforce the use of military commissions at Guantánamo. It forbids Holder’s Department of Justice from using taxpayers money to try any of Guantánamo’s 172 captives in civilian courts.

Only one Guantánamo detainee has faced a federal trial and a civilian jury cleared Tanzanian Ahmed Ghailani last year of all but one conspiracy charge for the 1998 East Africa bombings of two U.S. embassies. Ghailani is serving a life sentence.

Florida Sen. Marco Rubio, a co-sponsor, wants the White House the alleged Sept. 11 plotters tried at the Navy base in southeast Cuba. “The 9/11 conspirators should be immediately tried in military courts and not afforded the same rights as an American citizen in a civilian courtroom,” he said in a statement

“For too long, our government has stood idle while the 9/11 conspirators, including Khalid Sheik Mohammed, sit in Guantánamo Bay.”

Bradsher, the Pentagon spokeswoman, was unable to say whether the administration would craft a solution in advance of a death penalty conviction. Or whether Gates or his successor would fashion a solution only after a captive was convicted and condemned to die.

Military judges assigned to the on-again, off-again commissions have been particularly impatient with the evolving rules and policies that govern proceedings at Guantánamo since the Pentagon set up the detention center in January 2002.

With four men currently convicted of war crimes, once since 2008, the Defense Department is still developing a doctrine on the conditions of confinement that segregates them from the 168 other uncharged captives at Guantánamo.